NSGA-II phase balancing of primary distribution circuits by the reconnection of their circuit laterals and distribution transformers

•The present work implements an NSGA-II application for the phase balancing problem.•The application search for the minimal reconnection operations needed.•The energy losses and the neutral current are minimized.•The presented application has shown a very successful performance.

The primary distribution circuits are unbalanced not only by the spread use of unbalanced three-phase transformer banks and single-phase distribution transformers, but also by the use of two-phase three-wire and single-phase two-wire circuit laterals. The unbalance of the phase currents produces two fundamental problems in the circuit: the energy losses in the primary conductors are increased and the presence of a high neutral current on normal operation make it difficult the detection of earth faults by the neutral over current relays. The present work implements an NSGA-II application for the phase balancing problem, which search for the minimal reconnection needed for the two-phase three-wire and the single-phase two-wire circuit laterals, as well as for the three-phase transformer banks and the single-phase distribution transformers, to minimize both: the energy losses and the maximum neutral current of the circuit. The successful performance of this application is achieved by the new definition of the set of independent variables, which permits the NSGA-II to optimize the selection of the elements to be reconnected. A test example with all the needed data is solved to shows the features of the presented approach.